Strange behaviour with Caps Lock in Outlook 2010 and Win 8.1

Since I installed Win 8.1 in my 64-bit Dell my 32-bit Outlook 2010 exhibits strange behaviour when I turn on Caps Lock in the Subject field. If I click the Caps Lock when in the Subject field that window is minimised and I must reopen it.

The Window is still there and I can reopen it and carry on as normal. The only alternative is to hold the Shift Key down and type my capitalised heading but that is very inconvenient. I never saw this behaviour in Win 7.

To eliminate a problem with Outlook add-ins try starting outlook in safe mode. Use Win+R keys, then type "Outlook /safe" (without the quotation marks and with a space between the "k" & "/"), hit enter.